SOME PHYSICAL PROPERTIES OF ICE 609 



Various investigations related to glacier problems were planned 

 and worked on for many years in this department by Professors T. C. 

 Chamberlin and R. T. Chamberlin. The present work is a part of 

 that series and gives the result of preHminary investigations on the 

 elastic properties of ice. Since torsional force applied to a circular 

 rod is the only type of strain, as Professor Michelson^ says, in which 

 the cross-section remains constant, the main part of the present 

 study consists of observations on torsional deformation. Later some 

 attempts were made to determine the Young's modulus and also 

 to observe what would happen in bending. 



The preliminary work was begun early in the autumn of 1919, 

 but owing to a delay in securing certain necessary apparatus, it 

 was not until about the beginning of February, 1920, that the work 

 really began in earnest. About the end of March it became so 

 warm that it was no longer possible to continue the work on ice. 

 Because the time available for this cold work was so short, the 

 results are to be considered only as preUminary; yet they were so 

 suggestive that the present writer considered it worth while to 

 publish them even with these limitations. 



During the research, Professor R. T. Chamberlin took constant 

 interest and gave important suggestions for which the writer is 

 very much obliged. 



LIMIT OF ELASTICITY 



According to Professor Michelson,^ the deformation of an 

 elastic body passes through four different stages as it goes on, and 

 in the first portion the deformation is characterized by being 

 approximately proportional to the stress. The limit of this part 

 is well defined in some materials while in others it is not so dis- 

 tinctly marked.^ The following description will show that ice 

 also has a rather well-defined limit of elasticity in some cases at 

 least. 



Method. — In the present experimentation a circular rod of ice 

 was held horizontally with its one end fixed to a rigid stand and 

 the other end attached to a circular disk of radius 7 .45 cm. movable 



' A. A. Michelson, Jour. GeoL, Vol. XXV (191 7), P- 405- 



=> Ibid. 



3 A. E. H. Love, The Mathematical Theory of Elasticity, p. 112. 



